This invention relates to nanoscalar, pyrogenically produced yttrium-zirconium mixed oxide, a process for its production, as well as its use.
The production of pyrogenic oxides and mixed oxides by flame hydrolysis of vaporisable metal chlorides or metalloid chlorides is known. (Ullmanns EnzykIopadie der technischen Chemie, 4th Edition, Volume 21, page 44 (1982)).
Also known is a process for producing nanoscalar, pyrogenically produced oxides and/or mixed oxides of metals and/or metalloids, which is characterised in that organometallic and/or organometalloid substances, optionally dissolved in a solvent, optionally in a flame, are converted into the oxides at temperatures of above 200° C. The educts may be organometalloid and/or organometallic pure substances or any mixtures of these, or be used as solutions in organic solvents (EP 001 07 237.0-2111).
Zirconium oxide produced by this process has the disadvantage that the original tetragonal phase rearranges to form the monoclinic phase after a month, even during normal storage. This conversion runs parallel with a volume expansion. Because mouldings are destroyed during this process, the use of these products in ceramic applications is ruled out.
An object, therefore, of the present invention is to produce nanoscalar, pyrogenically produced zirconium oxide which does not have these disadvantages.